Semiconductor unit having a power semiconductor and semiconductor apparatus using the same

ABSTRACT

A semiconductor unit of certain aspects of the invention includes electrically conductive plates in the shape of the letter L, each consisting of a horizontally disposed leg portion and a vertically disposed flat body portion that is perpendicular to a cooling plate adhered to the bottom of the semiconductor unit. A pair of the vertically disposed flat body portions sandwiches a semiconductor chip. Owing to this construction, the heat generated in the semiconductor chip can be conducted away through the both surfaces of the chip, thus improving cooling performance. Since the heat is conducted away through the leg portions of the L-shaped electrically conductive plates a projected planar area occupied by the cooling plate required for cooling the semiconductor unit is reduced. Therefore, the size of the semiconductor unit can be reduced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor unit containing asemiconductor chip, and a semiconductor apparatus using thesemiconductor unit.

2. Description of the Related Art

It is known, for example in Japanese Unexamined Patent ApplicationPublication No. 2000-156439 (see FIG. 1), referred to herein as “PatentDocument 1,” to construct a semiconductor module, in a package,containing power semiconductor elements such as an IGBT (an insulatedgate bipolar transistor), a FWD (a free-wheeling diode) and the likemounted on an insulated substrate.

FIG. 17 is a sectional view of an essential part of a semiconductormodule of a first conventional example. FIG. 17 shows a semiconductormodule similar to that disclosed in Patent Document 1.

Referring to FIG. 17, an insulated substrate 55 is joined onto a coolingplate 54 with a solder or the like, and an IGBT chip 56 is mounted onthe cooling plate 54 through the insulated substrate 55. A collectorelectrode 58 of the IGBT chip 56 is electrically connected to a metalthin plate 55 a on the insulated substrate 55 with an electricallyconductive material such as a solder or the like.

An external electrode terminal 62 for a collector is electricallyconnected to a metal thin plate 64 b of a junction substrate 63 b joinedonto the cooling plate 54 with a solder or the like through a bus bar 60for the collector. An aluminum wire 65 makes electrical connectionbetween the collector electrode 58 of the IGBT chip 56 and the metalthin plate 64 b of the junction substrate 63 b.

On the other hand, an external electrode terminal 61 for an emitter iselectrically connected to a metal thin plate 55 b of the insulatedsubstrate 55 joined on the cooling plate 54 with a solder or the like,through a bus bar 59 for the emitter. A cooling member 67 of metal isjoined to an emitter electrode 57 of the IGBT chip 56 through anelectrically conductive junction member 66, and then, joined to a metalthin plate 64 a of a junction substrate 63 a with a solder or the like.

As a result, the emitter electrode 57 is electrically connected to themetal thin plate 64 a of the junction substrate 63 a through the coolingmember 67, and then, electrically connected to the external electrodeterminal 61 for the emitter through the bus bar 59 for the emitter. Thereference numeral 68 represents a casing for containing the IGBT chip56, and the reference numeral 69 represents silicone gel that seals offthe contained members in the casing 68.

In this semiconductor module, the cooling member 67 composed of metalplates makes conjunction between the emitter electrode 57 on the uppersurface of the IGBT chip 56 and the insulative junction substrate 63 adisposed on the cooling plate 54. Consequently, the heat generated inthe IGBT chip 56 is withdrawn from both upper and lower surfaces of theIGBT chip to the cooling plate 54.

Japanese Unexamined Patent Application Publication No. 2005-073373 (seeFIG. 1), referred to herein as “Patent Document 2,” discloses asemiconductor module of a second conventional example used in a powerconversion apparatus. This power conversion apparatus comprises: asemiconductor module containing semiconductor elements and having mainelectrode terminals and control electrode terminals; a control circuitboard connected to the control terminal electrodes of the semiconductormodule; a bus bar assembly composed of a plurality of bus bars connectedto the main electrode terminals of the semiconductor modules; and aplurality of cooling tubes for cooling the semiconductor module from theboth surfaces of the semiconductor module. The cooling structure for thesemiconductor module of the power conversion apparatus has coolingbodies sandwiching the semiconductor module and cooling thesemiconductor module from the both surfaces thereof.

In the first conventional example, the emitter electrode 57 on the uppersurface of the IGBT chip 56 and the insulative junction substrate 63 aprovided on the cooling plate 54 are joined with the cooling member 67composed of metal plates. The heat generated in the IGBT chip 56 istransported through the cooling member 67 and the insulative junctionsubstrate 63 a to the cooling plate 54. Consequently, a certain area isrequired as shown by the symbol ‘A’ in FIG. 18, for joining the coolingmember 67 with the insulation junction substrate 63 a (indicated in FIG.17). This requirement for ensuring the heat transfer area raises aproblem of increase in a module size.

An aluminum wire is used for connecting the collector electrode and thelead out terminal. The distance indicated by the arrow ‘B’ in FIG. 18 isrequired between the two places connected by the aluminum wire in orderto avoid stress development in the wire and at the joints. Thisrequirement for ensuring the distance raises a problem of increase in amodule size.

A current density of the main current that runs in the aluminum wire canbe hardly increased. In order to ensure sufficient magnitude of electriccurrent capacity, the number of aluminum wires needs to be increased,which however, increases the number of wiring places of the wires andthe number of manufacturing steps. In addition, need for reserving aregion to connect a multiple of aluminum wires raises a problem of anenlarged module size.

Moreover, the apparatus is provided with a control pin block (notdepicted in the figure) on a side wall surface of the casing, thecontrol pin block being required for inputting control signals tocontrol the IGBT chip 56. Need for an area to dispose the block makesminimization of the module difficult.

Patent Document 2 does not describe an internal structure of thesemiconductor module. The semiconductor elements cannot be practicallyused without providing appropriate cooling bodies on the both surfacesof the semiconductor element. Thus, a power conversion apparatus, forexample, a three phase inverter, using the semiconductor elements isenlarged.

Patent Document 1 and Patent Document 2 do not mention such a structurethat a pair of electrically conductive plates sandwiches thesemiconductor element from the both surfaces thereof and a leg portionof the electrically conductive plate bent in the shape of the letter ‘L’is attached to a heat sink to cool the semiconductor element, and thestructure is molded with a resin.

SUMMARY OF THE INVENTION

In view of the above-described problems, it is an object of embodimentsof the present invention to solve the above-problems and provide asemiconductor unit in a small size exhibiting good cooling performance.Another object of the invention is to provide a semiconductor apparatususing such a semiconductor unit.

In order to accomplish the objects, a semiconductor unit according tothe invention comprises: electrically conductive plates in the shape ofthe letter L having a flat body portion and a leg portion perpendicularto the flat body portion; a pair (s) of a semiconductor chip and aspacer that are laminated and fixed with each other, the pair beingsandwiched by the flat body portions of two of the electricallyconductive plates disposed opposing with each other; control terminals,one side ends of which are connected to control electrodes of thesemiconductor chip; and resin that seals off the flat body portions ofthe electrically conductive plates, the spacer, the semiconductor chip,and the one side ends of the control terminals; wherein the leg portionsof the electrically conductive plates and the other ends of the controlterminals are projecting out of the resin.

A semiconductor apparatus according to embodiments of the inventioncomprises: the semiconductor unit as defined above; lead out terminalseach connected to the leg portion of the semiconductor unit; a coolingplate to which lower surfaces of the leg portions of the semiconductorunit or lower surfaces of the lead out terminals are fixed interposingan insulation layer; a casing fixed to the cooling plate and containingthe semiconductor unit and the lead out terminals, ends of the lead outterminals and ends of the control terminals being projecting out of thecasing; and insulation material put in the casing.

According to an embodiment of the invention, in the semiconductorapparatus described above, preferably the lead out terminal is connectedto the leg portion of the semiconductor unit through an internalconnection conductor.

A semiconductor apparatus according to embodiments of the inventioncomprises: a plurality of the semiconductor units as described above; awiring conductor(s) connecting the leg portions of a plurality of thesemiconductor units; lead out terminals each connected to the legportion of the plurality of the semiconductor units; a cooling plate towhich at least one of a lower surface of the leg portion, a lowersurface of the wiring conductor, and a lower surface of the lead outterminal are fixed interposing an insulation layer; a casing fixed tothe cooling plate and containing the semiconductor unit, the wiringconductors, and the lead out terminals, ends of the lead out terminalsand ends of the control terminals being projecting out of the casing;and insulation material put in the casing.

According to an embodiment of the invention, in the semiconductorapparatus described above, preferably the lead out terminal is connectedto the leg portion of the semiconductor unit or the wiring conductorthrough an internal connection conductor.

According to an embodiment of the invention, in the semiconductorapparatus described above, preferably a part of the wiring conductorextends to project out and lead out from the casing.

According to an embodiment of the invention, the semiconductor apparatusas described above preferably further comprises a drive circuit boarddisposed above the casing and connected to the control terminals of thesemiconductor unit.

According to an embodiment of the invention, the semiconductor apparatusdescribed above preferably further comprises: a lid covering the casingat the top thereof; a drive circuit board that is disposed inside thecasing, immersed in the insulation material, and connected to thecontrol terminals of the semiconductor unit; and control conductors thatare fixed to the drive circuit board and projecting out through the lid.

According to an embodiment of the invention, in the semiconductorapparatus as described above, preferably the insulation material is gel.

According to an embodiment of the invention, in the semiconductor unitdescribed above, the semiconductor chips are preferably an IGBT chip anda FWD chip connected in anti-parallel to the IGBT chip.

According to an embodiment of, in the semiconductor apparatus asdescribed above, the lead out terminals are one of a P terminal, an Nterminal, and an M terminal that are components of an inverter.

According to an embodiment of the invention, in the semiconductorapparatus as described above, the lead out terminals are preferablydisposed separating vertically in the casing.

According to an embodiment of the invention, in the semiconductorapparatus as described above, the lead out terminals are preferablyfixed to the leg portion of the semiconductor unit by means of laserwelding.

According to an embodiment of the invention, in the semiconductorapparatus as described above, the leg portions of the semiconductor unitare preferably fixed to the lead out terminal and the wiring conductorby means of laser welding.

A semiconductor unit of embodiments of the present invention comprises apair of electrically conductive plates each having the shape of theletter ‘L’ and consisting of a vertical flat body portion and ahorizontal leg portion. The flat body portions are disposedperpendicularly to a cooling plate adhered to the bottom of thesemiconductor unit. A pair of the vertically disposed flat body portionssandwiches the semiconductor chip. Owing to this construction, the heatgenerated in the semiconductor chip is conducted away through the bothsurfaces of the chip and through the electrically conductive plates.Therefore, cooling performance of a semiconductor apparatus is improvedusing such a semiconductor unit.

The pair of vertical flat body portions of the electrically conductiveplates sandwich the semiconductor chip and the horizontal leg portionsconduct away the heat to the cooling plate. Therefore, a projectedplanar area of the cooling plate required for cooling the semiconductorunit is reduced, resulting in a reduced size of a semiconductorapparatus using the semiconductor unit.

When the cooling plate is replaced by a heat sink, the coolingefficiency is further improved.

The main electric current in the semiconductor chip is lead to runthrough the electrically conductive plates. Consequently, thesemiconductor apparatus can handle a heavy current.

A semiconductor apparatus that is a small sized power semiconductormodule of a type of power conversion apparatus is readily constructedusing several units of the semiconductor unit of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1( a) through 1(e) are external views of a semiconductor unit 100of Example 1 according to embodiments of the present invention, in whichFIG. 1( a) is a front view, FIG. 1( b) is a left side view, FIG. 1( c)is a right side view, FIG. 1( d) is a top plan view, and FIG. 1( e) is abottom plan view;

FIGS. 2( a) and 2(b) are sectional views of an essential part of thesemiconductor unit 100 of FIGS. 1( a) through 1(e);

FIGS. 3( a), 3(b), and 3(c) are sectional views of an essential partshowing manufacturing steps in the sequence of manufacturing thesemiconductor unit 100 of FIGS. 1( a) through 1(e);

FIG. 4 is a sectional view of an essential part of a semiconductorapparatus 200 of Example 2 according to embodiments of the presentinvention;

FIG. 5 illustrates a method of fixing the leg portions 1 b and 2 b ofthe semiconductor unit 100 onto the cooling plate 15 through aninsulation layer 14;

FIG. 6 is a sectional view of an essential part of a semiconductorapparatus 300 of Example 3 according to embodiments of the presentinvention;

FIG. 7 is a sectional view of an essential part of a semiconductorapparatus 400 of Example 4 according to embodiments of the presentinvention;

FIG. 8 is a sectional view of an essential part of a semiconductorapparatus 500 of Example 5 according to embodiments of the presentinvention;

FIG. 9 is a sectional view of an essential part of a semiconductorapparatus 600 of Example 6 according to embodiments of the presentinvention;

FIG. 10 is a sectional view of an essential part of a semiconductorapparatus 700 of Example 7 according to embodiments of the presentinvention;

FIG. 11 is a sectional view of an essential part of a semiconductorapparatus 800 of Example 8 according to embodiments of the presentinvention;

FIG. 12 is a sectional view of an essential part of a semiconductorapparatus 900 of Example 9 according to embodiments of the presentinvention;

FIG. 13 is a sectional view of an essential part of a semiconductorapparatus 1000 of Example 10 according to embodiments of the presentinvention;

FIG. 14( a) and FIG. 14( b) are equivalent circuit diagrams of asemiconductor apparatus applying the embodiments of present invention,in which FIG. 14( a) shows an equivalent circuit of two series-connectedsemiconductor units 100 and FIG. 14( b) shows an equivalent circuit oftwo parallel-connected semiconductor units 100.

FIGS. 15( a) and 15(b) show a construction of a semiconductor apparatus1100 of Example 11 according to the present invention, in which FIG. 15(a) is a plan view of an essential part and FIG. 15( b) is a sectionalview of the essential part cut along the line Y-Y in FIG. 15( a);

FIGS. 16( a) and 16(b) show a construction of a semiconductor apparatus1200 of Example 12 according to the present invention, in which FIG. 16(a) is a plan view of an essential part and FIG. 16( b) is a sectionalview of the essential part cut along the line X-X in FIG. 16( a);

FIG. 17 is a sectional view of an essential part of a semiconductormodule of a first conventional example;

FIG. 18 illustrates disadvantages of the conventional semiconductormodule of FIG. 17; and

FIGS. 19( a) and 19(b) are perspective views of a pair of electricallyconductive plates, in which FIG. 19( a) shows the leg portions extendingtowards both opposite outsides, and FIG. 19( b) shows the leg portionsextending towards one and the same side.

DETAILED DESCRIPTION OF THE INVENTION

Some aspects of preferred embodiments will be described showing someexamples of embodiment.

Example 1

FIGS. 1( a) through 1(e) are external views of a semiconductor unit 100of Example 1 according to embodiments of the present invention, in whichFIG. 1( a) is a front view, FIG. 1( b) is a left side view, FIG. 1( c)is a right side view, FIG. 1( d) is a top plan view, and FIG. 1( e) is abottom plan view.

FIGS. 2( a) and 2(b) are sectional views of the semiconductor unit 100of FIGS. 1( a) through 1(e), in which FIG. 2( a) is a sectional view cutalong the line X-X in FIG. 1( b) and FIG. 2( b) is a sectional view cutalong the line Y-Y in FIG. 1( a).

This semiconductor unit 100 comprises a pair of electrically conductiveplates in the shape of the letter L. The electrically conductive plateconsists of a flat body portion and a leg portion that is continuous andperpendicular to the flat body portion. An undepicted collectorelectrode of an IGBT chip 6 is soldered to an L-shaped electricallyconductive plate 1 for collector with a solder 8. An L-shapedelectrically conductive plate 2 for emitter is soldered with a solder 8to one surface of a spacer 7, the other surface of which is solderedwith a solder 8 to an undepicted emitter electrode of the IGBT chip 6.

The electrically conductive plate 1 for collector is also soldered witha solder 8 to an undepicted cathode electrode of a FWD 9, which isdisposed adjacent to the IGBT chip 6. The electrically conductive plate2 is also soldered with a solder 8 to one surface of a spacer 10, theother surface of which is soldered with a solder 8 to an undepictedanode electrode of the FWD chip 9.

Control electrodes of the IGBT 6 are connected to control terminals 3with wires 4. These components are sealed off with resin 5 to constructthe semiconductor unit 100.

The electrically conductive plate 1 for collector in the shape of theletter L and the electrically conductive plate 2 for emitter in theshape of the letter L consist of flat body portions 1 a, 2 a sandwichingthe IGBT chip 6 and the FWD chip 9, and the leg portions 1 b, 2 bleading externally. The leg portion 1 b, 2 b is continued to the edge ofthe flat body portion 1 a, 2 a and perpendicular to the flat bodyportion 1 a, 2 a. The leg portions 1 b, 2 b are protruding out of theresin 5.

The leg portions 1 b, 2 b of the semiconductor unit 100 are attached toan undepicted circuit board for packaging. Consequently, thesemiconductor unit 100 is electrically connected to the undepictedcircuit board through the leg portions 1 b, 2 b, and the heat generatedin the IGBT chip 6 and the FWD chip 9 is conducted to an undepictedcooling plate or cooling fins through the leg portions 1 b, 2 b.

The control terminals 3 include a gate terminal, an auxiliary emitterterminal, a temperature sensor terminal, and a current detectionterminal. Some of the control terminals 3 are connected to controlelectrodes 6 a (see FIG. 2( a)) of the IGBT chip 6 through the wire 4and are fixed with the resin 5. Every control terminal 3 is projectingout of the resin 5.

Thicknesses T of the L-shaped electrically conductive plate 1 forcollector and the L-shaped electrically conductive plate 2 for emitterare in the range of 1 mm to 5 mm. A length of the leg portions is in therange of 1 cm to 2 cm.

The solder 8 can be an electrically conductive adhesive such as silverpaste.

The L-shaped electrically conductive plate 1 for collector, the L-shapedelectrically conductive plate 2 for emitter, and the control terminals 3are often formed using a lead frame.

The IGBT chip 6 and the FWD chip 9 have a flat configuration and theflat surfaces are disposed vertically to the surface of packaging of thesemiconductor unit 100 with a circuit board or the like. The controlterminals 3 are lead out upward from the resin 5. As a consequence, thewidth W between the ends of the leg portions 1 b and 2 b of thesemiconductor unit 100 is reduced. Therefore, a packaging area for thesemiconductor unit 100 is significantly reduced as compared with theconstruction of FIG. 17 in which power semiconductor elements arearranged on an insulation substrate.

The semiconductor unit 100 is packaged with an undepicted circuit boardthrough the leg portions 1 b and 2 b and thus, connected to the circuitboard electrically and thermally. The heat generated in the IGBT chip 6and the FWD chip 9 is conducted through the leg portions 1 b and 2 b toan undepicted cooling plate or cooling fins. Consequently, aconstruction of a semiconductor apparatus of the invention does not needa structure disposing cooling bodies on the both surfaces of asemiconductor unit as in the second conventional example. Therefore, thesemiconductor apparatus of the invention can be used in variety of powerconversion apparatuses ensuring high reliability.

Although the above-described example of semiconductor unit 100 containstwo chips of an IGBT chip 6 and a FWD chip 9, the IGBT chip 6 and theFWD chip 9 can be contained in separate respective semiconductor units.

In the semiconductor unit 100 as shown in FIGS. 1( a) through 1 (e), theIGBT chip 6 and the FWD chip 9 are arranged along a direction parallelto the packaging surface of the semiconductor unit 100. In such anarrangement, a distance from the IGBT chip 6 to the cooling surface (thepackaging surface of the leg portions 1 b, 2 b) and a distance from theFWD chip 9 to the cooling surface is approximately equal, allowinguniform cooling.

Though a drawing is omitted, an arrangement is also possible in whichthe IGBT chip 6 and the FWD chip 9 are disposed along a directionvertical to the packaging surface of the semiconductor unit 100 (theflat surfaces of the chips are also vertical to the packaging surface).In such an arrangement, an area for packaging the semiconductor unit canbe further reduced.

FIGS. 3( a) through 3(c) illustrate a process of manufacturing asemiconductor unit 100 of FIGS. 1( a) through 1(e). FIGS. 3( a) through3(c) are sectional views of essential parts following the manufacturingsequence.

As shown in FIG. 3( a), an L-shaped electrically conductive plate 1 forcollector is placed on a jig 11 with the flat body portion 1 a of theconductive plate 1 in a horizontal position. After putting a solderplate on the flat body portion, an IGBT chip 6 and a FWD chip 9 aremounted on the flat body portion is so that the collector electrode ofthe IGBT chip 6 and the cathode electrode of the FWT chip 9 are incontact with the solder plate. Subsequently, the assembly is transportedthrough a reflow furnace to melt the solder plate. After cooling theassembly, the chips are fixed with the solder 8.

Referring to FIG. 3( b), in the state with the L-shaped electricallyconductive plate 1 put on the jig 12, the control terminals 3 arefurther placed on the jig 12. The control terminals 3 are connected toundepicted control electrodes of the IGBT chip 6 with wires 4.

Then, a solder plate(s) is put on the emitter electrode of the IGBT chip6 and on the anode electrode of the FWD chip 9, and spacers 7, 10, whichare heat spreaders, are placed on the solder plate(s). Subsequently,solder plates are put on the spacers 7 and 10, and a flat body portion 2a of an L-shaped electrically conductive plate 2 for emitter is placedon the solder plates. Here, the bottom surface of the leg portion 1 b ofthe L-shaped electrically conductive plate 1 for collector and thebottom surface of the leg portion 2 b of the L-shaped electricallyconductive plate 2 for emitter are made in one common plane. Thisassembly is put into a reflow furnace to melt the solder plates. Takingout from the reflow furnace and cooling down the melt solder plates, theL-shaped electrically conductive plate 1 for collector, the IGBT chip 6,the FWD chip 9, spacers 7, 10, and the L-shaped electrically conductiveplate 2 for emitter are fixed with the solder 8.

After soldering with a solder 8, the whole assembled articles are putinto a mold 13 as shown in FIG. 3( c) and sealed off with a resin 5 bymeans of transfer molding, having the leg portions 1 b, 2 b of theelectrically conductive plates 1,2 and the control terminals 3projecting out of the resin 5. Here, the bottom surface of the resin 5between the electrically conductive plates 1 and 2 is made in one commonplane with the bottom surfaces of the electrically conductive plates 1and 2. Then, the control terminals 3 and the L-shaped electricallyconductive plate 1 are cut off to complete manufacturing steps of thesemiconductor unit 100.

In order to obtain the common bottom plane, another process can betaken.

In the step shown in FIG. 3( b), the bottom surface of the leg portion 1b of the electrically conductive plate 1 for collector and the bottomsurface of the leg portion 2 b of the L-shaped electrically conductiveplate 2 for emitter are made in an approximately common plane. Then, inthe step shown in FIG. 3( c), after molding with a resin, a grindingprocess is conducted to create a common plane among the bottom surfaceof the leg portion 1 b of the L-shaped electrically conductive plate 1for collector, the bottom surface of the leg portion 2 b of the L-shapedelectrically conductive plate 2 for emitter, and the bottom surface ofthe resin 5 between the electrically conductive plates 1 and 2.

The control electrodes of the IGBT chip 6 including a gate electrode, anauxiliary emitter electrode, a temperature sensor electrode, and acurrent detection electrode are connected to the control terminals 3 bywire bonding process. Position adjustment of the plurality of controlterminals can be facilitated in the wire bonding process between thecontrol electrodes of the IGBT chip 6 and the control terminals 3 owingto the use of a lead frame having a connection array of tie-bars in theouter lead side, that is, the side of the control terminals 3 projectingout of the resin 5. Separate control terminals 3 are obtained by cuttingthe tie-bars of the connection array in the outer lead after moldingwith the resin 5.

Example 2

FIG. 4 is a sectional view of an essential part of a semiconductorapparatus of Example 2 according to the present invention. This examplecontains one unit of the semiconductor unit shown in FIGS. 1( a) through1(e).

This semiconductor apparatus 200 comprises: a semiconductor unit 100described previously, a cooling plate 15 fixed through an insulationlayer 14 with the bottom surfaces of the leg portions 1 b and 2 b of thesemiconductor unit 100 (the leg portion 1 b of the L-shaped electricallyconductive plate 1 for collector and the leg portion 2 b of the L-shapedelectrically conductive plate 2 for emitter); a lead out terminal 17 forcollector and a lead out terminal 18 for emitter connected to the legportions 1 b and 2 b; a casing 20 containing the semiconductor unit 100and the lead out terminals 17, 18 and connected to the cooling plate 15;and gel 21 (insulation material, for example, silicone gel) put in thecasing 20. The control terminals 3 and the lead out terminals 17, 18 areprojecting out of the casing.

In this embodiment example, the leg portion 1 b is connected to the leadout terminal 17 for collector through an internal connection conductor16. The leg portion 2 b is similarly connected to the lead out terminal18 for emitter through the internal connection conductor 16.

The insulation layer 14, a resin insulation sheet of high thermalconductivity in this example, can be replaced by an insulated substratewith an electrically conductive pattern such as a DCB substrate (directcopper bonding substrate).

In the semiconductor apparatus 200, the heat generated in the IGBT chip6 and the FWD chip 9 (only IGBT 6 can be seen in FIG. 4) is transferredfrom the surface of the IGBT chip 6 and the surface of the FWD chip 9 tothe L-shaped electrically conductive plate 1 for collector and theL-shaped electrically conductive plate 2 for emitter, and then,conducted to the cooling plate 15 through the leg portions 1 b and 2 bof the respective L-shaped electrically conductive plates. Since theheat generated in the IGBT chip 6 and the FWD chip 9 is removed from theboth surfaces of each chip, improved cooling performance is achieved.

Vertical arrangement of the IGBT chip 6 and the FWD chip 9 reduces thearea occupied by the cooling plate 15 for cooling the semiconductor unit100, thus minimizing the semiconductor apparatus 200.

The main electric current flowing in the IGBT chip 6 and the FWD chip 9runs not through a wire but through the L-shaped electrically conductiveplate 1 for collector, the L-shaped electrically conductive plate 2 foremitter, and the internal connection conductor 16. Therefore, a highcurrent can flow in the apparatus.

The IGBT chip 6 and the FWD chip 9 are covered with the resin 5, andthis resin 5 is covered with the gel 21. Therefore, the junction surfaceof the solder 8 is more reliable as compared with the case of thesemiconductor unit 100 alone.

Putting in the gel 21, an insulation material, avoids discharge aroundthe part A (in FIG. 4) where a gap is small between the cooling plate 15and the lead out terminal 17, and between the cooling plate 15 and thelead out terminal 18. Accordingly, the gel 21 can be provided to anamount just covering the part A at the minimum. The gel 21, however, canbe more provided as much as filling the whole interior of the casing 20.

Since a variety of tests including a surge test and a short-circuit testcan be carried out on the semiconductor unit 100 alone, solely goodsemiconductor units 100 that have passed through the tests can be usedto construct a semiconductor apparatus 200. Therefore, a percentage ofgood products of an assembled semiconductor apparatus 200 containing thesemiconductor unit 100 is enhanced.

FIG. 5 illustrates a method of fixing the leg portions 1 b, 2 b of thesemiconductor unit 100 to the cooling plate 15 through the insulationlayer 14, which is an insulation resin sheet having a high thermalconductively. The insulation layer 14, which is a high thermalconductivity insulation resin sheet, is inserted between the coolingplate 15 and the bottom surfaces of the leg portions 1 b, 2 b of thesemiconductor unit 100. The upper surfaces of the leg portions 1 b, 2 bare pushed with a specified force as shown by the arrows P in FIG. 5while being heated. Thus, the semiconductor unit 100 is fixed to thecooling plate 15 with heat and pressure through the high thermalconductivity insulation resin sheet (an insulation layer 14). One sheetof the high thermal conductivity insulation resin sheet is used for oneunit of the semiconductor unit 100 in this example. However, one sheetof the insulation resin sheet can be used for a plurality ofsemiconductor units 100.

Example 3

FIG. 6 is a sectional view of an essential part of a semiconductorapparatus of Example 3 according to the invention. This semiconductorapparatus 300 is different from the semiconductor apparatus 200 of FIG.4 in that a drive circuit board 22 is disposed above the casing 20. Thedrive circuit board 22 has circuit components mounted thereon to controland protect the IGBT chip 6.

The control terminals 3 lead out from the semiconductor unit 100 arejoined to a circuit pattern (not shown in the figure) on the drivecircuit board 22.

Example 4

FIG. 7 is a sectional view of an essential part of a semiconductorapparatus of Example 4 according to the invention. This semiconductorapparatus 400 is different from the semiconductor apparatus 200 of FIG.4 in that the lead out terminals 17 and 18 are joined to the legportions 1 b and 2 b by laser welding 19. This means makes thesemiconductor apparatus 300 more minimized. In this apparatus too, adrive circuit board can be disposed as in FIG. 6.

Example 5

FIG. 8 is a sectional view of an essential part of a semiconductorapparatus of Example 5 according to the invention. This semiconductorapparatus 500 is different from the semiconductor apparatus 200 of FIG.4 in that a heat sink 23 is used in place of the cooling plate 15. Theheat sink 23 can be provided with water-cooled fins or air-cooled fins.The heat sink 23 replaced for the cooling plate 15 achieves enhancedcooling efficiency of the semiconductor apparatus 500.

Example 6

FIG. 9 is a sectional view of an essential part of a semiconductorapparatus of Example 6 according to the invention. This semiconductorapparatus 600 is an example having series-connected two semiconductorunits 100.

The semiconductor apparatus 600 comprises: two semiconductor units 100;lead out terminals 25, 26 connected to the leg portions 1 b, 2 b of thesemiconductor unit 100; a cooling plate 15 adhered to the lower surfacesof the leg portions 1 b, 2 b of the semiconductor unit 100 through aninsulation layer 14; a casing 20 connected to the cooling plate 15; gel21, an insulation material, provided in the casing 20; and a drivecircuit board 22 connected to the control terminals 3 above the casing20. The lead out terminals 25, 26 are disposed through a side wall ofthe casing 20 in this embodiment example. The lead out terminal 25 isconnected to the leg portion 1 b of the semiconductor unit 100 throughan internal connection conductor 16 that is joined by laser welding 19to the lead out terminal 25 and the leg portion 1 b. The lead outterminal 26 is connected to the leg portion 2 b in the similar way. Awiring conductor 28 performs connection between a leg portion of onesemiconductor unit 100 and a leg portion of the other semiconductor unit100, the two semiconductor units being connected in series. Theconnection between the wiring conductor 28 and the leg portions of thesemiconductor units 100 are carried out by laser soldering as well.

In the example shown in FIG. 9, the connection between the leg portionof the semiconductor unit 100 and the lead out terminal is conductedthrough the internal connection conductor 16. The internal connectionconductor 16, however, can be omitted and the lead out terminals 25, 26can be directly joined to the leg portions of the semiconductor units100 by laser welding. The direct laser welding can remove the internalconnection conductor, and further, can get rid of a laser welding stepthat would be necessary for connection between the internal connectionconductor 16 and the leg portions of the semiconductor units 100.

Moreover, a part of the wiring conductor can be extended to lead out ofthe casing 20. This means makes it possible to extract the electricpotential at the connection point between the series-connectedsemiconductor units 100 to outside of the casing.

FIG. 14( a) is a circuit diagram of an example of such a seriesconnection between the semiconductor units 100. Although the example ofFIG. 9 shows the semiconductor units 100 connected in series, thesemiconductor units 100 can be connected in parallel as shown in FIG.14( b).

Examples of series connection of semiconductor units 100 as in FIG. 14(a) will be further described afterwards.

As described earlier, the insulation layer 14, which is an insulationresin sheet exhibiting high thermal conductivity, works to fix the legportions 1 b, 2 b to the cooling plate 15 with heat and pressure. Inplace of the insulation layer 14, a DCB substrate (a direct copperbonding substrate) can be used. The leg portions 1 b, 2 b are solderedto an electrically conductive pattern on the front surface of the DCBsubstrate and a copper foil on the rear surface is used to fix to thecooling plate 15.

The gel 21 works to avoid discharge at the position B (in FIG. 9) wherea gap between the cooling plate 15 and the leg portions 1 b, 2 b isshort and a gap between the cooling plate 15 and the lead out terminals25, 26 is short.

As described above on this example, connection through the internalconnection conductor 16 is made between the lead out terminal 25 and theupper surface of the leg portion 1 b of the semiconductor unit 100, andbetween the lead out terminal 26 and the upper surface of the legportion 2 b of the semiconductor unit 100. Connection between thesemiconductor units is made through the wiring conductor. The connectionthrough the internal connection conductors 16 and the connection throughthe wiring conductor 28 are carried out by means of laser welding 19.This connection process can be carried out by means of ultrasonicjoining as well. When the connection is carried out by means ofsoldering, a solder to be used must have a melting point lower than thatof a solder 8 that is used in the semiconductor unit 100.

A construction without the drive circuit board 22 is also possible inthis example of semiconductor apparatus. In that case, the controlterminals 3 are connected to an undepicted external control circuit withelectric wiring.

This semiconductor apparatus 600 is often used provided with a heat sinkunder the cooling plate 15.

Example 7

FIG. 10 is a sectional view of an essential part of a semiconductorapparatus of Example 7 according to the invention. This semiconductorapparatus 700 is different from the semiconductor apparatus 600 of FIG.9 in that a lid 24 is provided on the casing 20 and the interior of thecasing 20 is completely filled with a gel 21. Control terminals 3 areprojecting out through the lid 24. Provision of the lid 24 firmly fixesthe drive circuit board 22.

Example 8

FIG. 11 is a sectional view of an essential part of a semiconductorapparatus of Example 8 according to the invention. This semiconductorapparatus 800 is different from the semiconductor apparatus 700 of FIG.10 in that the drive circuit board 22 is contained within the casing 20.The drive circuit board 22 is provided with externally connecting pins27. The control terminals 3 of the semiconductor unit 100 are connectedto the drive circuit board inside the casing 20. The externallyconnecting pins 27 provided on the drive circuit board 22 are projectingout through the lid 24 and connected to undepicted external wirings.

Since the drive circuit board 22 is embedded in the gel 21, any foreignmatter is avoided to be attached on the drive circuit board 22, thusimproving reliability of the apparatus.

When the drive circuit board 22 is fixed to the casing 20 in the casing20 (though not depicted in FIG. 11), if any stress is subjected to theexternally connecting pins 27 that is connected to the external wiring,the stress is not transferred to the control terminals 3 of thesemiconductor unit 100.

Example 9

FIG. 12 is a sectional view of an essential part of a semiconductorapparatus of Example 9 according to the invention. This semiconductorapparatus 900 is different from the semiconductor apparatus 800 of FIG.11 in that a heat sink 23 is used in place of the cooling plate 15. Theheat sink 23 shown here is water cooled fins. Air cooled fins can beused as well. This construction improves cooling efficiency.

Example 10

FIG. 13 is a sectional view of an essential part of a semiconductorapparatus of Example 10 according to the invention. This semiconductorapparatus 1000 is a semiconductor module constructing a three phaseinverter, a type of power conversion apparatus. The semiconductor moduleassembles six semiconductor units 100 including IGBT chips 6 and FWDchips 9. FIG. 14( a) is a circuit diagram of one phase (or one arm) ofthe three phase inverter of FIG. 13.

This semiconductor apparatus 1000 comprises: six semiconductor units100; wiring bars 31, 33, 35 that are connecting to the leg portions 1 bof the semiconductor units 100; wiring bars 37, 38, 39 that are wiringconductors each series-connecting the leg portion 1 b of a semiconductorunit 100 to the leg portion 2 b of another semiconductor unit 100;wiring bars 32, 34, 36 that are lead out terminals connecting to legportions 2 b of the semiconductor units 100; a cooling plate 15 to whichthe leg portions 1 b, 2 b of the semiconductor units 100 are fixedthrough the insulation layer 14 with heat and pressure; a casing(undepicted; see the casing 20 in FIG. 11, for example) containing theinsulation layer 14 and the semiconductor units 100 and fixed to thecooling plate 15; and gel (undepicted; see the gel 21 in FIG. 11, forexample) filling the interior of the casing.

The wiring bars 31, 33, 35 are P terminals (corresponding to ‘+’terminals), which are lead out terminals, of the three phase inverter;the wiring bars 32, 34, 36 are N terminals (corresponding to ‘−’terminals), which are lead out terminals, of the three phase inverter;and the wiring bars 37, 38, 39 are wiring conductors for connectionbetween the semiconductor units 100 and partly extended to become Mterminals (corresponding to U-phase, V-phase, and W-phase) of the threephase inverter.

This semiconductor apparatus 1000 is generally used with an undepictedheat sink provided under the cooling plate 15.

In the example of FIG. 13, the wiring bars 31 through 38 are directlylead out from an undepicted casing. Those wiring bars 31 through 38 aredirectly joined to the leg portions of the semiconductor units 100 bylaser welding. Therefore, the internal connection conductors as shown inFIG. 9 can be eliminated.

The cooling plate 15 in FIG. 13 can be replaced by a heat sink (see theheat sink 23 in FIG. 12, for example). Since the cooling plate 15 iseliminated in that case, cooling performance can be improved.

An non-depicted drive circuit board (see the drive circuit board 22 inFIG. 11, for example) can be provided above the semiconductor units 100.In that case, the control terminals 3 are connected to an externalcontrol circuit with electric wirings.

Since this semiconductor apparatus 1000 does not have two cooling bodieson both surfaces of the semiconductor unit 100 but has only one heatsink under the semiconductor unit 100, a semiconductor apparatuscorresponding to the one disclosed in Patent Document 2 can be reducedin its size.

Example 11

FIGS. 15( a) and 15(b) show a construction of a semiconductor apparatusof Example 11 according to the present invention, in which FIG. 15( a)is a plan view of an essential part, and FIG. 15( b) is a sectional viewof the essential part cut along the line Y-Y in FIG. 15( a).

This semiconductor apparatus 1100 is different from the semiconductorapparatus 1000 of FIG. 13 in that the wiring bars connecting to thesemiconductor units 100 are arranged separating vertically and inthree-dimensional arrangement. This configuration reduces the planararea occupied by the wiring bars and thus makes the semiconductorapparatus smaller in its size. In this construction, having the wiringbars at different height, the lower wiring bar is first laser welded,and then, higher wiring bar is laser welded, thus, two times of laserwelding processes are conducted.

Example 12

FIGS. 16( a) and 16(b) show a construction of a semiconductor apparatusof Example 12 according to the present invention, in which FIG. 16( a)is a plan view of an essential part, and FIG. 16( b) is a sectional viewof the essential part cut along the line X-X in FIG. 16( a).

This semiconductor apparatus 1200 is different from the semiconductorapparatus 1100 of FIGS. 15( a) and 15(b) in that the wiring bars 31through 36 connecting to the semiconductor unit 100 are arranged bentvertically. In this construction too, the planar area occupied by thewiring bars 31 through 36 is small and thus, the semiconductor apparatus1200 is reduced in its size.

The vertical levels of the surfaces of welding the wiring bars 31through 36 are the same and thus, the process of the laser welding 19can be only once.

FIGS. 19( a) and 19(b) are perspective views of electrically conductiveplates showing examples of leg portions leading out from thesemiconductor unit. Structures except for the electrically conductiveplates are omitted in the figures.

In the examples described thus far, the leg portion 1 b of an L-shapedelectrically conductive plate 1 for collector and the leg portion 2 b ofan L-shaped electrically conductive plate 2 for emitter are extendingtowards opposite directions as shown in FIG. 19( a). An electricallyconductive plate having a shape as shown in FIG. 19( a) can bemanufactured at a low cost owing to a simple configuration thereof and apackaging process subsequent to production of the semiconductor unit canbe carried out stably.

FIG. 19( b) shows a variation of the present invention with the legportions of the electrically conductive plates that are extending to thesame direction. The electrically conductive plates of this example alsohave a sectional configuration of the letter L. The flat body portion 1a of the electrically conductive plate 1 has a cut for extracting theleg portion 2 b of the electrically conductive plate 2. Thus, the legportion 2 b of the electrically conductive plate 2 is extending towardsthe same direction as the leg portion 1 b of the electrically conductiveplate 1. A projected planar area required for packaging thesemiconductor unit is substantially reduced by the configuration of theleg portions 1 b and 2 b extending towards the same direction. However,the structure of FIG. 19( b), due to a smaller area under the legportions 1 b, 2 b as compared with the structure of FIG. 19( a),provides a smaller area for thermal contact with the cooling platethrough an undepicted insulation layer. Accordingly, the structure ofFIG. 19( b) is suitable for the cases in which a small amount of heat isgenerated in the semiconductor chip joined to the electricallyconductive plates 1, 2 or an area of packaging the semiconductor unit isto be greatly reduced.

This application is based on, and claims priority to, Japanese PatentApplication No. 2010-113183, filed on May 17, 2010. The disclosure ofthe priority application, in its entirety, including the drawings,claims, and the specification thereof, is incorporated herein byreference.

What is claimed is:
 1. A semiconductor unit comprising: electricallyconductive plates, each of the plates being in the shape of the letterL, having a flat body portion and a leg portion perpendicular to theflat body portion; a pair of a semiconductor chip and a spacer that arelaminated and fixed with each other, the pair being sandwiched by a flatbody portion of each of two of the electrically conductive plates, theelectrically conductive plates being disposed opposing each other;control terminals, one side end of one or more of the control terminalsbeing connected to control electrodes of the semiconductor chip; andresin that seals off the flat body portions of the electricallyconductive plates, the spacer, the semiconductor chip, and the one sideends of the control terminals; wherein ends of the leg portions of theelectrically conductive plates and ends of the control terminalsopposite the one side ends are projecting out of the resin, and whereinthe semiconductor chip is an IGBT chip, and a FWD chip is connected inanti-parallel to the IGBT chip.
 2. A semiconductor apparatus comprising:the semiconductor unit of claim 1; lead out terminals each connected toa leg portion of the semiconductor unit of claim 1 through an internalconnection conductor; a cooling plate to which lower surfaces of the legportions of the semiconductor unit of claim 1 or lower surfaces of thelead out terminals are fixed interposing an insulation layer; a casingfixed to the cooling plate and containing the semiconductor unit ofclaim 1 and the lead out terminals, ends of the lead out terminals andends of the control terminals being projecting out of the casing; andinsulation material in the casing.
 3. The semiconductor apparatusaccording to claim 2, further comprising a drive circuit board disposedabove the casing and connected to the control terminals of thesemiconductor unit of claim
 1. 4. The semiconductor apparatus accordingto claim 2, wherein the insulation material is gel.
 5. The semiconductorapparatus according to claim 2, wherein the lead out terminals are fixedto the leg portion of the semiconductor unit by means of laser welding.6. A semiconductor apparatus comprising: a plurality of semiconductorunits, each of the plurality of semiconductor units configured as thesemiconductor unit of claim 1; a wiring conductor connecting the legportions of the plurality of semiconductor units; lead out terminalseach connected to the leg portion of the plurality of semiconductorunits; a cooling plate to which at least one of a lower surface of theleg portion, a lower surface of the wiring conductor, and a lowersurface of the lead out terminal are fixed interposing an insulationlayer; a casing fixed to the cooling plate and containing the pluralityof semiconductor units, the wiring conductors, and the lead outterminals, ends of the lead out terminals and ends of the controlterminals being projecting out of the casing; and insulation material inthe casing, wherein a part of the wiring conductor extends to projectout and lead out from the casing.
 7. The semiconductor apparatusaccording to claim 6, wherein each of the lead out terminals isconnected to a leg portion of one of the plurality of semiconductorunits or the wiring conductor through an internal connection conductor.8. The semiconductor apparatus according to claim 6, wherein the leadout terminals are at least one of a P terminal, an N terminal, and an Mterminal that are a component of an inverter.
 9. The semiconductorapparatus according to claim 6, wherein the lead out terminals aredisposed separating vertically in the casing.
 10. The semiconductorapparatus according to claim 6, wherein the leg portions of one of theplurality of semiconductor units are fixed to the lead out terminal andthe wiring conductor by means of laser welding.
 11. A semiconductorapparatus comprising: a plurality of the semiconductor units, each ofthe plurality of semiconductor units comprising: electrically conductiveplates, each of the plates being in the shape of the letter L, having aflat body portion and a leg portion perpendicular to the flat bodyportion; a pair of a semiconductor chip and a spacer that are laminatedand fixed with each other, the pair being sandwiched by a flat bodyportion of each of two of the electrically conductive plates, theelectrically conductive plates being disposed opposing with each other;control terminals, one side end of one or more of the control terminalsbeing connected to control electrodes of the semiconductor chip; andresin that seals off the flat body portions of the electricallyconductive plates, the spacer, the semiconductor chip, and the one sideends of the control terminals; wherein the leg portions of theelectrically conductive plates and ends of the control terminalsopposite the one side ends are projecting out of the resin; thesemiconductor apparatus further comprising: a wiring conductorconnecting the leg portions of a plurality of the semiconductor units;lead out terminals each connected to a leg portion of the plurality ofthe semiconductor units; a cooling plate to which at least one of alower surface of the leg portion, a lower surface of the wiringconductor, and a lower surface of the lead out terminal are fixedinterposing an insulation layer; a casing fixed to the cooling plate andcontaining the semiconductor unit, the wiring conductors, and the leadout terminals, ends of the lead out terminals and ends of the controlterminals being projecting out of the casing; and insulation material inthe casing; a lid covering the casing at the top thereof; a drivecircuit board that is disposed inside the casing, immersed in theinsulation material, and connected to the control terminals of thesemiconductor unit; and control conductors that are fixed to the drivecircuit board and projecting out through the lid.